At present, film layers in a display device are mostly formed by a patterning process. The patterning process is a process for making a thin film into a layer comprising at least one pattern. The patterning process typically comprises forming a mask pattern on a thin film, etching a portion of the thin film which is not covered by the mask pattern, and then peeling off the remaining mask pattern, thereby obtaining a desired pattern of the thin film.
In the practical production, it is usually required to form a thin film pattern having a step. At this time, it is required to form a mask pattern 1 having a step as shown in FIG. 1. At present, the aforementioned mask pattern is always formed by a halftone mask plate. However, the process for manufacturing the halftone mask plate is relatively complex.